I sometimes fly a Firefly (original one-piece canopy) which leaks in rain - you get rain down the back of your neck, of all places...
As for the heavy showers, that's why you learn diversion techniques on your PPL, isn't it (e.g. 45 deg left, time 5 minutes, 90 deg right, time 5 minutes, 45 deg left, confirm position...)
Tim